Kiln cart pusher

ABSTRACT

Embodiments of a pusher device may include a frame, guide rails coupled to the frame, a carriage slideable along the guide rails, and a linear positioner coupled to the carriage and frame and operable to move the carriage along the guide rails. Two or more lugs may be mounted to the carriage and rotatable between a resting position, in which the forward ends of the lugs can contact the transverse supports of a tram above the carriage, and a lowered position in which the lugs can pass below the transverse supports. In the resting position, the longitudinal axis of each lug may be inclined from rear to front, such that the lugs contact the tram with the front end (as opposed to a longitudinal side) of the lugs. The lugs be generally triangular, trapezoidal, or concave polygonal in profile. Corresponding methods and systems are also disclosed herein.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 15/364,237 filed Nov. 29, 2016, which is acontinuation of and claims priority to U.S. patent application Ser. No.15/182,323, filed Jun. 14, 2016, now U.S. Pat. No. 9,534,842, whichclaims priority to U.S. Patent Application No. 62/300,770, filed Feb.27, 2016, all titled “KILN CART PUSHER,” the entire disclosures of whichare incorporated by reference herein.

BACKGROUND

Conventional track-type lumber kilns are provided with a set of railsthat extend through the kiln. Lumber packages are loaded onto wheeledcarts, or trams, which typically include a series of transverse supportsmounted to a wheeled frame. The trams are moved through the kiln alongthe track in an end-to-end arrangement. As each tram is moved into thekiln, it is forced against the lagging end of the next to advance theentire line of trams.

A pusher device is typically used to push the trams through the kiln.One type of conventional pusher device uses a hydraulic cylinder toexert force against the trams. However, conventional pusher devices maybe prone to breakage or failure under harsh conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. Embodimentsare illustrated by way of example and not by way of limitation in thefigures of the accompanying drawings.

FIGS. 1A-1B are perspective views of a prior kiln pusher;

FIG. 2 is a perspective view of an embodiment of a pusher device;

FIGS. 3A-3B are perspective and plan views, respectively, of componentsof a pusher device as shown in FIG. 2;

FIG. 4 is a perspective view of the pusher device of FIG. 2 in use;

FIG. 5 is a perspective view of another embodiment of a pusher device;

FIGS. 6 and 7 are perspective views of components of a pusher device asshown in FIG. 6;

FIG. 8 is a perspective view of the pusher device of FIG. 6 in use;

FIG. 9 is a perspective view of another embodiment of a pusher device inuse;

FIG. 10 is a perspective view of another embodiment of a pusher device;

FIG. 11A is a perspective view of components of a pusher device as shownin FIG. 10;

FIGS. 11B-C are side and rear elevational views of components shown inFIG. 11A;

FIGS. 11D-E are additional side elevational views of components shown inFIG. 11A;

FIG. 11F is a schematic sectional view of some of the components shownin FIG. 11B, taken along lines A-A of FIG. 11B;

FIGS. 12A-12B are plan and side elevational views, respectively, of apusher device as shown in FIG. 10;

FIG. 12C is a magnified view of a portion of FIG. 12B;

FIG. 13 is an exploded view of a pusher device as shown in FIG. 10;

FIG. 14 is a perspective view of an alternative embodiment of a pusherdevice carriage;

FIG. 15 is a plan view of the pusher device carriage of FIG. 14;

FIGS. 16A-B are rear elevational and side elevational views,respectively, of the pusher device carriage of FIG. 14; and

FIGS. 17A-B are side elevational and perspective views, respectively, ofcomponents of a pusher device, all in accordance with variousembodiments.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which are shownby way of illustration embodiments that may be practiced. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope. Therefore,the following detailed description is not to be taken in a limitingsense, and the scope of embodiments is defined by the appended claimsand their equivalents.

Various operations may be described as multiple discrete operations inturn, in a manner that may be helpful in understanding embodiments;however, the order of description should not be construed to imply thatthese operations are order dependent.

The description may use perspective-based descriptions such as up/down,back/front, and top/bottom. Such descriptions are merely used tofacilitate the discussion and are not intended to restrict theapplication of disclosed embodiments.

The terms “coupled” and “connected,” along with their derivatives, maybe used. It should be understood that these terms are not intended assynonyms for each other. Rather, in particular embodiments, “connected”may be used to indicate that two or more elements are in direct physicalor electrical contact with each other. “Coupled” may mean that two ormore elements are in direct physical or electrical contact. However,“coupled” may also mean that two or more elements are not in directcontact with each other, but yet still cooperate or interact with eachother.

For the purposes of the description, a phrase in the form “A/B” or inthe form “A and/or B” means (A), (B), or (A and B). For the purposes ofthe description, a phrase in the form “at least one of A, B, and C”means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).For the purposes of the description, a phrase in the form “(A)B” means(B) or (AB) that is, A is an optional element.

The description may use the terms “embodiment” or “embodiments,” whichmay each refer to one or more of the same or different embodiments.Furthermore, the terms “comprising,” “including,” “having,” and thelike, as used with respect to embodiments, are synonymous.

The present disclosure describes embodiments of a pusher device for useto move trams or carts along a track. Corresponding methods and systemsare also disclosed herein. In exemplary embodiments, a computing devicemay be endowed with one or more components of the disclosed apparatusesand/or systems and may be employed to perform one or more methods asdisclosed herein.

Rail-mounted trams, or kiln carts, are often used to convey lumberthrough a kiln for drying. A typical tram has a pair of wheeledlongitudinal supports connected by a series of transverse membersmounted on the longitudinal supports at increments, with gaps betweenadjacent transverse members. Collectively, the transverse members form alumber support surface.

The tram's wheels are mounted on rails that extend through the kiln.Green lumber is placed onto the transverse members of the tram, and thetram is pushed or pulled along the track through the kiln. Somefacilities push the trams through the kiln in series, abuttingend-to-end, using a pusher device positioned along the track upstream ofthe kiln entrance. One type of conventional pusher device uses acarriage with rotatable lugs to exert force against the upstream-mosttram.

For the purposes of the present description, a lug has opposed faces, atleast two sides that are transverse to the faces, at least one end thatis transverse to the faces and sides, a pivot axis that extends throughthe opposed faces, and a longitudinal axis. The “cross-sectional shape”of a lug (i.e., the shape of the lug “in profile”) is the shape of theouter periphery of the lug within a plane that extends through the lugnormal to the pivot axis and equidistant from the opposed faces. Thecross-sectional shape of a lug is generally a polygon with multiplesides, the longest of which is one “side” of the lug. If the polygon hasonly three sides, the second-longest side is another “side” of the lug,the last (shortest) side is one “end” of the lug, and the intersectionof the longest and second-longest sides of the polygon is considered theother (or opposite) “end” of the lug. If the polygon has four or moresides, the longest side is a “side” of the lug, the sides of the polygonthat are adjacent to the longest side are the “ends” of the lug, and theremaining side(s) of the polygon is/are the other “side(s)” of the lug.

Each of the sides, ends, and faces lies within a corresponding plane,and each may be either continuous (e.g., a flat uninterrupted surface)or discontinuous (e.g., textured, notched, etc.) within that plane. Inother words, two or more surfaces that lie within the same plane arepart of the same side, end, or face. In addition, unless statedotherwise, the cross-sectional shape of a lug is defined withoutreference to the shape(s) of the intersections of the sides and ends(“corners”), any or all of which may be curved/rounded, chamfered,beveled, or angular in profile. For example, a lug with parallel faces,parallel sides, and parallel ends is considered to have a rectangularcross-sectional shape, whether the corners are curved, beveled, angular,etc.

The “longitudinal axis” of a lug is defined as an axis that extendsthrough the lug, and through the pivot axis, parallel to the longestside of the lug.

FIGS. 1A-1B illustrate a conventional pusher device 10 positionedbetween the rails of a track.

The conventional pusher device 10 includes a frame 12, a carriage 14with front and rear wheels 16, and a hydraulic cylinder 18. The carriage14 has front, side, and rear vertical walls coupled together to form agenerally square frame with an open center. The rod of the hydrauliccylinder is connected to the rear wall of the carriage, and the cylinderbody is coupled to a pair of elongate support plates that are in turncoupled to the side walls. Pairs of lugs 20 are rotatably mounted to thecarriage on a shaft 22 that passes through the lugs and the side wallsof the carriage. The lugs are rotatable in a forward direction (in theview of FIG. 1A, counter-clockwise) on the shaft from a resting positionas shown to a lowered position (not shown). Stops 24 are fixedly coupledto the side walls within the frame, forward of the pivot axis of thelugs (i.e., between the front wall of the carriage and the shaft 22).Stops 24 are thus positioned to engage the front sides of the lugs nearthe bottom ends of the lugs to prevent backward rotation of the lugs.

The lugs of pusher device 10 are substantially rectangular in profile,with rounded corners at the intersection of the upper end and the sides.The lugs have parallel faces, parallel top and bottom ends, and parallelfront and back sides that are longer than the ends. In the restingposition, the lugs are upright, such the longitudinal axis and the frontand rear sides of each lug are substantially vertical and the ends arevertically aligned with the pivot axis. In the lowered position (notshown), the lugs 20 are rotated forward, such that the top ends of thelugs are forward of the pivot axis and the longitudinal axis is inclinedfrom rear to front.

The hydraulic cylinder 18 is selectively actuable to move the carriage14 forward and backward within the frame 12 on wheels 16 to push a tram(FIG. 1B). As illustrated, a tram 2 has a pair of longitudinal supports6 with wheels 8, and transverse members 4 arranged on the longitudinalsupports to form a support surface. The transverse members 4 aresubstantially coplanar and positioned at regular intervals along thelength of the tram. The wheels 8 of each longitudinal support engage thecorresponding rail of the track.

In the resting position, the upper ends of the lugs extend into orthrough the plane of the transverse members 4. In the lowered position,the lugs are below the plane of the transverse members 4. The othercomponents of carriage 14, as well as the frame 12 and hydrauliccylinder 18, remain below the plane of the transverse members regardlessof the position of the lugs. The lugs are rotatable from the restingposition to the lowered position by application of pressure against therear/lagging side of the lugs.

In operation, the pusher device is positioned between the rails of thetrack upstream of the kiln entrance. A push cycle begins when thehydraulic cylinder 18 is extended to move the carriage 14 forward by anincrement of distance. The lugs 20 are in the resting position as thecarriage 14 moves forward. The forward movement of the carriage 14brings the front sides of the lugs into engagement with the rear side ofa transverse support 4 to push the corresponding tram forward. Thehydraulic cylinder 18 is then retracted to move the carriage 14backward, which brings the rear side of the lugs into contact with thefront side of another transverse support 4. The force exerted againstthe lugs by this contact causes them to rotate forward to the loweredposition, which is maintained by the contact between the rear side ofthe lugs and the underside(s) of the transverse support(s) as thecarriage continues to move backward. When the lugs reach a gap betweentransverse supports, the lugs return to the resting position. Theretraction of hydraulic cylinder 18 to the initial position completesone push cycle. Successive push cycles can be used to move a line oftrams incrementally along the rails in an end-to-end arrangement.

This design has several disadvantages. First, if the transverse supportsbecome warped, bent, or damaged, or if the carriage encounters debrisbetween the rails, one of the lugs may contact the tram before theothers. The resulting force may bend or break the lug. In addition, amoment developed by the hydraulic cylinder piston tends to cause thefront of the carriage to lift. The resulting increase in force againstthe rear wheels may cause them to seize or break. In addition, damage tothe wheels, uneven contact of the lugs with the trams, or debris alongthe track can cause lateral or twisting carriage motion, which can causefailure of the rear guide wheels, breakage of the vertical lugs at thewelds, or sticking/seizing of the vertical lugs in one position.

Embodiments described herein may overcome some or all of thesedisadvantages of conventional pusher devices. In various embodiments, apusher device may be configured such that when the lugs are in theresting position, the longitudinal axis of each lug is inclined ortilted forward (as opposed to vertical) to contact the tram with thefront end (as opposed to a side) of the lugs. The lugs may be rotatablymounted to a carriage that is slideably mounted on linear bearings.

The lugs may have a front end, a back end, a lower side, and an upperside. The upper side may be longer than the ends and, optionally, thelower side. When the lugs are in the resting position, the upper sidemay be inclined from rear to front and the back end may be generallyhorizontal.

In some embodiments the lugs may be generally trapezoidal in profile,with neither end forming a right angle to either of the sides. In otherembodiments the lugs may be generally triangular in profile, with thefront end and the upper and lower sides forming the three sides of thetriangle, and the intersection of the upper and lower sides consideredthe back end of lug. In still other embodiments the lugs may havegenerally the shape of a concave polygon in profile, with the front endbeing curved or angled in contour to define an interior angle of morethan 180 degrees.

The lugs may be rotatably mounted to a pusher carriage disposed within aframe. The pusher carriage may have guide members (e.g., linear bushingsor bearing carriages) that are slideable along corresponding guide rails(e.g., profile rails). A linear positioner (e.g., a hydraulic cylinder,pneumatic cylinder, roller screw, planetary screw, etc.) may be used tomove the carriage forward and backward within the frame along the guiderails. In some embodiments the guide rails may be attached to anunderlying support that is coupled to the frame.

In some embodiments one or more stop members may be provided rearward ofthe shaft/pivot around which the lugs rotate. The stop member may bepositioned to engage the back end of a corresponding lug in the restingposition to prevent backward rotation of the lug. Other embodiments maylack a stop member. For example, in some embodiments the lugs may beshaped and dimensioned such that the bottom sides of the lugs are incontact with the carriage while the lugs are in the resting position,preventing backward rotation of the lugs.

Configurations and features described herein may provide for reducedstress on the lugs, thereby reducing fatigue-related lug failure, incomparison to conventional configurations with vertical lugs. Therotation required for the lugs to move under the trams may becomparatively less, which may reduce sticking and/or slow return of thelugs to the resting position. The use of linear bushings/bearingsinstead of wheels for movement of the carriage may reduce lifting,twisting, and other non-linear carriage motion, which may help to limitthe frequency and severity of damage to the lugs, carriage, and othercomponents of the pusher device during use under harsh conditions.

FIG. 2 illustrates a perspective view of a pusher device 100, inaccordance with various embodiments.

Pusher device 100 may include a frame 102, a carriage 104, a hydrauliccylinder 108 connected at opposite ends 112, 114 to the rear of thecarriage and the rear of the frame, respectively, and lugs 116. Lugs 116may be mounted to the carriage on shaft 134, such that the lugs 116 arerotatable in a forward direction.

Shaft 134 may extend through opposite sides of the carriage. Asillustrated, some embodiments may have two pairs of lugs 116 arranged onopposite sides of the carriage, with the lugs of each pair positioned onopposite sides of the corresponding side wall. Other embodiments mayhave two, three, five, six, or more than six lugs.

Carriage 104 may have front, back, and opposed side walls joinedtogether to form a frame. The carriage may be slideable along a pair ofguide rails 130. The guide rails may help to reduce or prevent lifting,twisting, and/or lateral movements of carriage 104 that could damagecomponents of the pusher device and cause early failure of the system.Using guide rails instead of (or in addition to) wheels may reduce oreliminate wheel failures that can occur in prior pushers operated underharsh conditions. In some embodiments, a bellows (not shown) may beprovided on or over the guide rails to protect the guide rails from dirtor other debris that could otherwise stick to the guide rails.

Guide rails 130 may be mounted to the frame 102 above the underlyingfloor surface with mount blocks 146 that are bolted to the frame 102.The forward ends of the guide rails 130 may be retained in/throughcorresponding mount blocks 146 that are bolted to a front end of theframe, and the rearward ends of the guide rails 130 may be retainedin/through corresponding mount blocks 146 that are bolted to the support138. Support 138 may be rigidly attached (e.g., welded or bolted) to theframe 102. The use of mount blocks may allow for convenient disassemblyof the guide rails for maintenance or replacement. Mounting the guiderails to forward end of the frame and to support 138 may reducedeflection of the guide rails during use.

Optionally, a support 140 may also be rigidly attached (e.g., welded orbolted) to the frame rearward of support 138. Supports 138 and 140 maybe plates, bars, beams, or the like, made of steel or any other suitablematerial. The ends 114 and 112 of the hydraulic cylinder 108 may bebolted or otherwise rigidly attached to the supports 140 and 138,respectively, using one or more mount blocks, plates, or the like. Asillustrated, in some embodiments the hydraulic cylinder may be coupledto support 138 by an L-shaped bracket 148 that has a vertical portionand a horizontal portion. The vertical portion may have an open-endedslot dimensioned to receive the outer body of the hydraulic cylinder,such that the hydraulic cylinder is cradled within the slot. Thehorizontal portion may be bolted to support 138. Optionally, the bracketmay have reinforcing gussets at each side. The bracket may help tosupport and stabilize the hydraulic cylinder during operation whilefacilitating its removal for maintenance purposes.

Referring now to FIGS. 3A-B, guide rails 130 may be disposed throughcorresponding guide members 132 in the front and rear walls of carriage104 (see FIG. 3A). In some embodiments, guide members 132 may be linearbushings. The guide rails may be greased to aid smooth travel of thecarriage on the guide rails. Optionally, carriage 104 may havereinforcing gussets 140 at some of the intersections of the front, back,and sides of carriage 104.

Lugs 116 may be rotatably mounted on shaft 134 (FIG. 2). In someembodiments, shaft 134 may be fixed relative to the carriage frame, andthe lugs may be rotatable on the shaft. In other embodiments, lugs 116may be fixed in position on shaft 134, and shaft 134 may be rotatablesuch that the lugs and shaft rotate as a single unit. Optionally, lugspacer rings 144 may be provided along the shaft on one or both sides ofthe lugs to maintain a desired spacing between lugs 116 and the sides ofthe carriage 104. This may facilitate cleaning and maintenance of thelugs and/or help to prevent jamming caused by lugs contacting thecarriage frame.

Some embodiments may include one or more counterweights 136.Counterweight 136 may be coupled to one or more of the lugs 116 (e.g.,at the back end of the lug) to aid in returning the lug(s) to theresting position.

Lugs 116 may have front and back ends 118 and 120, respectively, andupper and lower sides 122 and 124, respectively, as well as oppositefaces. The lugs may be trapezoidal in shape, such that the front andback ends do not form right angles with the upper and lower sides. Upperside 122 may be longer than the front and back ends 118, 120 and thelower side 124. In some embodiments, the lug may have curved or roundededges/corners at some or all of the intersections between the ends andthe sides.

Carriage 104 may have one or more stops 126. In various embodiments,stop(s) 126 may be positioned rearward of the pivot axis of the lugs.Stop(s) 126 may be positioned to contact the back end 120 of the lugswhen the lugs are in the resting position. Alternatively, stop(s) 126may be positioned to contact the lower side 124 proximal to the back end120 when the lugs are in the resting position. In either case, thestop(s) 126 may be configured to prevent backward rotation of the lugsfrom the resting position.

In some embodiments the front ends 118 and/or back ends 120 of the lugsmay be provided with an elastomeric or compressible pad 128. Thecompressible pad may help to reduce stress concentrations on the lugswhen pushing a tram that is bent or otherwise damaged.

When the lugs 116 are in the resting position, the upper and lower sidesof lugs 116 may be inclined and front ends 118 may be substantiallyvertical. In some embodiments the back ends 120 may be substantiallyhorizontal when lugs 116 are in the resting position.

Referring now to FIG. 4, the hydraulic cylinder may be actuated to pushthe carriage forward. As the carriage moves forward with the lugs in theresting position, the forward ends of the lugs are brought into contactwith the rear surface of a corresponding transverse member 4 of a tram,and the tram is pushed forward. As the hydraulic cylinder is retractedand the carriage is moved backward, the upper side 122 of the lugscontacts the leading edge of the next successive transverse member 4.The lugs are rotated forward to the lowered position by the engagementof the upper side 122 with the underside of the transverse member. Oncethe lugs have passed beneath the transverse member, they begin to rotateback to the resting position.

FIGS. 5-9 illustrate perspective views of another example of a pusherdevice 200 and components thereof, in accordance with variousembodiments. Elements that generally correspond to elements of FIGS. 2-4are indicated with like reference characters.

Pusher device 200 may have a frame 202, a carriage 204, a linearpositioner (e.g., a hydraulic cylinder) 208 connected at opposite endsto the rear of the carriage and the rear of the frame, respectively, andlugs 216.

The frame 202 may have generally vertical front, rear, and side walls.The linear positioner/hydraulic cylinder 208 may be coupled with theframe via supports 238 and 240 and bracket 248 in the same or similarmanner as described above. In addition, a plate 256 may be welded orotherwise rigidly attached to the frame. Plate 256 may be a sheet ofsteel or other such material. Optionally, plate 256 may extend belowboth side walls of the frame 102, and/or from the front end of the frameto the body of the linear positioner 208.

Carriage 204 may include a carriage plate 250, brackets 252, and acylinder mount 254. In some embodiments carriage plate 250 may be aplate of steel or other such material. Cylinder mount 254 may bedisposed at the back end of plate 250 and the brackets 252 may bedisposed on the upper surface of plate 250. Brackets 252 and cylindermount 254 may be coupled to the plate 250 by welds, bolts, or the like.Optionally, the carriage plate and the cylinder mount and/or bracketsmay have complementary notches, slots, or the like, along which thesecomponents are fitted together.

Guide rails 230 may be affixed to the rail plate 256 (FIG. 5), andcorresponding guide members 232 may be affixed to the bottom surface ofcarriage plate 250, with welds, bolts, or other suitable fasteners(FIGS. 6-7). In a particular example, the guide members 232 are Rexroth55 mm roller blocks, and the guide rails 230 are Rexroth 1845 size 55rails. Alternatively, other suitable sizes and/or types of linear motionbearings may be used instead.

Referring now to FIGS. 6-7, lugs 216 may be arranged along shaft 234,which may extend through the brackets 252. A pair of lugs and acorresponding bracket may be provided on both sides of the carriage. Thelugs of each pair may be positioned on opposite sides of thecorresponding bracket 252.

Lugs 216 may be generally triangular in shape, with the front end 218,upper side 222, and lower side 224 as the three sides of the triangle.The intersection of the upper and lower sides 222 and 224 may be theback end 220. The upper side may be longer than the lower side and thefront end. As best illustrated in FIG. 6, the lugs may be curved at theintersection of the front end 218 and the lower side 224. In the restingposition (shown), the front end 218 may be substantially vertical, thelower side 224 may be substantially horizontal, and the upper side 222may be inclined from rear to front. The thickness of the lugs (distancebetween the opposed faces) may vary among embodiments. In someembodiments, lugs 216 may be 1-3 inches thick. In a particular example,lugs 216 are approximately 2 inches thick.

The number and arrangement of the lugs and brackets 252 may vary amongembodiments. As shown by way of example in FIG. 9, in some embodimentsthe carriage may have additional brackets 252, such that each lug isdisposed between two brackets. Other embodiments may have one or moreadditional brackets and/or lugs located nearer to the center of thecarriage or the shaft.

Optionally, pusher device 200 may further include various other features(e.g., lug spacer rings, gussets, elastomeric pads, guide railprotective bellows, etc.) described above with regard to pusher device100. For example, as shown in FIG. 9, in some embodiments carriage 204may include gussets 258 connected to the upper surface of the carriageplate 250 and the forward surface of the cylinder mount 254.

Another example of a pusher device is shown in FIGS. 10-13. Referringfirst to FIG. 10, pusher device 300. Again, elements that generallycorrespond to elements of FIGS. 2-9 are indicated with like referencecharacters.

Pusher device 300 may have a frame 302 and a carriage 304. A linearpositioner (not shown) may be connected at opposite ends to the rear ofthe carriage and the rear of the frame, respectively.

Again, the frame 302 may have generally vertical front, rear, and sidewalls. Supports 338 and 340 and the linear positioner may be coupledwith the frame in the same or similar manner as described above.

A plate 356 may be welded or otherwise rigidly attached to the frame.Plate 356 may be a sheet of steel or other such material. Again, plate356 may be coupled to the underside of the frame and extend below bothside walls of the frame. However, plate 356 may have a series ofopen-ended slots 360 around the outer edge thereof (see also FIG. 12A).The slots 360 may extend inwardly toward a longitudinal center of theframe, passing beyond the vertical walls of the frame. Thisconfiguration may allow drainage of water or other fluids through theplate 356. Alternatively, plate 356 may be provided with interior holesto provide drainage.

Optionally, a removable bracket 262 may be coupled with the forward endof carriage plate 350 and plate 356 by bolts or the like. Bracket 262may be used to secure carriage plate 350 in place for shipping and/orduring maintenance, and removed before resuming operation of the pusherdevice.

Carriage 304 may include a carriage plate 350, brackets 352, and acylinder mount 354. In some embodiments carriage plate 350 may be aplate of steel or other such material. Cylinder mount 354 may bedisposed at the back end of plate 350 and the brackets 352 may bedisposed on the upper surface of plate 350. Brackets 352 and cylindermount 354 may be coupled to the plate 350 by welds, bolts, or the like.Again, the carriage plate and the cylinder mount and/or brackets mayhave complementary notches, slots, or the like, along which thesecomponents are fitted together, and/or reinforcing gussets 358. In someembodiments carriage plate 350 may include one or more grease fittingports 364. A grease fitting/zerk fitting may be disposed within eachport 364.

Guide rails 330 may be affixed to the rail plate 356 (FIG. 10).Referring now to FIGS. 11A-C, corresponding guide members 332 may beaffixed to the bottom surface of carriage plate 350 (e.g., with bolts orother suitable fasteners). In some embodiments, guide members 332 andguide rails 330 may be linear recirculating roller bearing and guidewayassemblies. For example, guide members 332 may be INA double sealedroller guide carriages with anti-corrosion coating, and guide rails 330may be corresponding INA 55 mm profile rails with brass closure plugs.Alternatively, any other suitable size or type of linear motion bearingmay be used instead.

A pair of brackets 352 may be provided on opposite sides of the uppersurface of carriage plate 350. Optionally, the brackets may beconstructed with chamfered lower surfaces and welded to the carriageplate to fill the chamfer with weld. In some embodiments, brackets 352may have an open-ended slot 372 (FIG. 11D).

A lug 316 may be disposed between the brackets of each pair. Lugs 316may be generally triangular in shape, with the front end 318, upper side322, and lower side 324 as the three sides of the triangle and theintersection of the upper and lower sides 222 and 224 forming back end220. The upper side may be longer than the lower side and the front end,and the lugs may be curved at the intersection of the front end 318 andthe lower side 324. In the resting position (shown), the front end 318may be substantially vertical, the lower side 324 may be substantiallyhorizontal, and the upper side 322 may be inclined from rear to front.

FIGS. 11E-F show additional details of the bracket and lugconfiguration. As best illustrated in FIG. 11F, which shows a sectionalview taken along a vertical plane that passes through the center of thepivot axis of the lugs, brackets 252 may be provided with bushingsleeves 368. Corresponding bushings 370 may be disposed within thebushing sleeves. In some embodiments, bushings 370 may beself-lubricating bushings. In other embodiments, bushings 370 may bepre-lubricated bushings, metallic bushings, composite bushings, or anyother suitable type of bearing. A shaft 334 may extend through thebushings 370 and lug 316. Another shaft 334 may extend through thebushings and lug on the opposite side of the carriage. A retainingflange 366 may be provided at each end of each shaft.

Again, the number and arrangement of the lugs 316 and brackets 352 mayvary among embodiments. Optionally, the lugs 316 may be more than threeinches thick. For example, the lugs may be approximately 4 inches thick,or 3-5 inches thick.

FIG. 13 is an exploded view of a pusher device as shown in FIG. 10. Insome embodiments, a pusher device may include a cover 374, such as asheet of metal or other durable material, configured to cover the linearpositioner 308 during use. The cover 374 may be removably coupled to theframe 302 with bolts, screws, brackets, or with any other suitable typeof fastener.

Some pusher devices may include a linear alignment coupler 376 coupledto the front end/rod of linear positioner 308. The use of a linearalignment coupler may reduce wear on linear positioner 308 and/orcomponents thereof. Other embodiments may lack linear alignment coupler376.

Optionally, a shaft 334 and corresponding lug 316 may be provided as aunitary component. For example, the shaft may be press-fitted throughthe corresponding lug. Alternatively, the shaft and lug may be weldedtogether. In other embodiments, the shaft and lug may be provided asseparate components.

The shapes and dimensions of the lugs and brackets may vary amongembodiments. For example, FIGS. 14-15 and 16A-B illustrate a carriage404 with brackets 452 that are generally rectangular. Optionally,brackets 452 may extend toward the back of the carriage 452 beyond theback ends of lugs 416. Carriage 404 may further include supports 478affixed to the upper surface of the carriage plate 450. Each support 478may be, or may include, a block or plate positioned in contact with theback end of a corresponding bracket 452. In some embodiments, supports478 may be constructed with a chamfered lower edge and welded to thecarriage plate 450 such that the chamfer is substantially filled.

Brackets 452 may be removably coupled to the carriage plate 350 withbolts 482 (FIGS. 16A-B). Removably coupling the brackets to the carriageplate may allow damaged or worn brackets to be replaced, and/or allowthe brackets and corresponding lug to be removed as a single unit.Supports 478 may help to reinforce the brackets, and may serve asalignment guides for installing or replacing the brackets.

In some embodiments a lug may have two ends and more than two sides.Some lugs may have the shape of a concave polygon in profile. Others mayhave the shape of a convex polygon in profile. Again, any or all of theintersections between two sides or an end and a side may be angled orcurved, chamfered, beveled, or the like.

A lug with a concave polygon cross-sectional shape/profile isillustrated by way of example in FIG. 17A. Lug 416 may have a front end418, a back end 420, an upper side 422, a lower side 424, and a thirdside 480. Front end 418 and third side 480 may form an interior angle ofmore than 180 degrees. For example, they may form an interior angle of190-230°, 200-220°, 205-212°, or about 208°. Optionally, the upper side422 and the bottom side 424 may be generally parallel to one another.Lower side 424 and third side 480 may form an angle of 80-100°, or85-95°, 88-92°, or about 90°. Lower side 424 and back end 420 may forman interior angle of 140-160°, 145-155°, 150-154°, or about 152°. Any orall of the corners (e.g., corner 482 of upper side 422 and front end482) may be curved, rounded, beveled, etc.

In the resting position, the back end 420 of the lug 416 may rest on asurface of the carriage plate 450, preventing further backward rotationof the lug. When the lug is rotated forward to the lowered position,lower side 424 may rest on another surface of carriage plate 450,preventing further forward rotation of the lug. As such, carriage plate450 may lack stop members. Optionally, carriage plate 450 may havereplaceable plates/pads at some or all of the surfaces contacted by anend or side of the lugs to thereby reduce wear on the carriage plateand/or lugs, or to facilitate smooth motion of the lugs.

Again, shaft 434 may be press fitted or welded to the corresponding lug416, or rigidly affixed thereto by any other suitable means.

A pusher device may have any of the features (e.g., lug spacer rings,gussets, elastomeric pads, guide rail protective bellows, etc.) of anyof the embodiments described herein, in any suitable combination.

In some embodiments, an existing pusher device may be modified byreplacing the carriage, lugs, wheels, and/or other existing componentswith components of pusher devices as described herein. For example,pusher device 10 could be modified by removing the existing carriage,coupling guide rails (and optionally a rail plate) to the frame of theexisting pusher device, and coupling a pusher carriage as describedherein to the guide rails and the existing hydraulic cylinder.Alternatively, pusher device 10 could be modified by replacing the lugswith lugs as described herein (either on the existing shaft or onseparate shafts) and reinstalling the stop members rearwardly of thepivot axis of the lugs, and/or replacing the wheels with linear bearingscoupled to the existing carriage and existing frame. In any case,existing components such as the frame, hydraulic cylinder and hydraulicsystem may be reused for a more cost-efficient upgrade of an existingpusher device.

Although certain embodiments have been illustrated and described herein,it will be appreciated by those of ordinary skill in the art that a widevariety of alternate and/or equivalent embodiments or implementationscalculated to achieve the same purposes may be substituted for theembodiments shown and described without departing from the scope. Thosewith skill in the art will readily appreciate that embodiments may beimplemented in a very wide variety of ways. This application is intendedto cover any adaptations or variations of the embodiments discussedherein. Therefore, it is manifestly intended that embodiments be limitedonly by the claims and the equivalents thereof.

What is claimed is:
 1. A pusher device, comprising: a carriage having atleast one pair of guide members configured to slideably engage acorresponding pair of guide rails; and first and second lugs coupled tothe carriage and rotatable, relative to the carriage, between a restingposition and a lowered position, wherein the first lug has opposedfaces, an axis of rotation that extends through the opposed faces,multiple sides that are transverse to the opposed faces, at least oneend that is transverse to the faces and the sides, and a longitudinalaxis that extends through the first lug and the corresponding pivot axisparallel to the longest of the sides of the first lug, wherein the lugis configured to rotate from the resting position to the loweredposition in response to force applied against an upper portion of thelongest of the sides of the lug, and to return to the resting positionupon removal of said force, and wherein the longitudinal axis of thefirst lug is inclined when the first lug is in the resting position. 2.The pusher device of claim 1, wherein the first and second lugs aremounted on corresponding first and second shafts and rotatableindependently of one another.
 3. The pusher device of claim 2, whereinthe first lug has a cross-sectional shape, within a plane that is normalto the pivot axis and equidistant between said faces, which is generallypolygonal with at least one rounded corner.
 4. The pusher device ofclaim 3, wherein the cross-sectional shape of the first lug includes atleast one interior angle greater than 180°.
 5. The pusher device ofclaim 4, wherein the multiples sides and at least one end includes anupper side, a lower side, a front end, a back end, and a third sideadjacent to the front end and the lower side, and the upper side is thelongest of the sides, and wherein the at least one interior angle isformed by the front end and the third end.
 6. The pusher device of claim5, wherein the front and back ends are substantially vertical andhorizontal, respectively, when the first lug is in the resting position.7. The pusher device of claim 3, wherein the cross-sectional shape ofthe first lug is generally triangular.
 8. The pusher device of claim 7,wherein the multiples sides and at least one end includes an upper side,a lower side, and a front end, and the upper side is the longest of thesides, and wherein the rounded corner is at the intersection of thefront end and the lower side.
 9. The pusher device of claim 8, whereinthe front end and the lower side are substantially vertical andhorizontal, respectively, when the first lug is in the resting position.10. The pusher device of claim 2, wherein the carriage includes agenerally horizontal plate with first and second brackets coupledthereto, and the first lug is coupled a shaft disposed through the firstbracket.
 11. The pusher device of claim 10, wherein the lug isconfigured to contact the upper side of the plate with one of the sidesor one of the one or more ends of the lug when the lug is in the restingposition.
 12. The pusher device of claim 10, wherein the first lug isdisposed between the first and second brackets, and the shaft isdisposed through the first and second brackets.
 13. The pusher device ofclaim 12, wherein the shaft is press fitted through the first lug. 14.The pusher device of claim 10, further including a generally rectangularframe with vertical front, side, and end walls, wherein the guide railsare coupled with the frame and oriented generally parallel to the endwalls, and the carriage is slideably coupled to the guide rails.
 15. Thepusher device of claim 14, further including a generally planar plateextending between the side walls of the frame, wherein the guide railsare mounted to an upper surface of the plate.
 16. The pusher device ofclaim 12, wherein the first and second brackets have correspondingbushings disposed within bushing sleeves, and the shaft is disposedthrough the bushings.
 17. The pusher device of claim 16, wherein thebushings are self-lubricating bushings.
 18. The pusher device of claim2, wherein the guide members are roller guide carriages, and the guiderails are profile rails.
 19. The pusher device of claim 18, wherein thecarriage comprises a generally horizontal carriage plate, the guidemembers are coupled to an underside of the carriage plate, and the firstand second lugs and the brackets are disposed on an opposite upper sideof the carriage plate and generally parallel with the lugs.
 20. Thepusher device of claim 19, wherein the brackets are coupled to thecarriage plate by corresponding bolts that extend through the carriageplate.
 21. A pusher system, comprising the pusher device of claim 1 anda linear positioner coupled to the carriage, wherein the linearpositioner is operable to move the carriage along the guide rails. 22.The pusher system of claim 21, wherein the linear positioner includes ahydraulic cylinder.
 23. A method of modifying an existing pusher device,wherein the existing pusher device includes an existing frame withfront, rear, and side walls, and an existing hydraulic cylinder, themethod comprising: coupling a pair of guide rails to the existing framebetween and generally parallel to the side walls; slideably coupling acarriage with the guide rails, wherein the carriage includes two or morelugs independently rotatable between a resting position and a loweredposition, each of the lugs having opposed faces, multiple sides, a pivotaxis, and a longitudinal axis that extends through the pivot axisparallel to the longest of the sides; and coupling the hydrauliccylinder to a back end of the carriage, such that the hydraulic cylinderis operable to move the carriage along the guide rails.
 24. The methodof claim 23, further including coupling a generally horizontal plate tothe existing frame, wherein coupling the guide rails to the existingframe includes attaching the guide rails to an upper surface of thegenerally horizontal plate.
 25. The method of claim 23, whereinslideably coupling the carriage with the guide rails includes attachingguide members to an existing carriage of the existing pusher device andcoupling the guide members with the guide rails, wherein the guidemembers are configured to slideably engage a corresponding one of theguide rails.
 26. The method of claim 23, wherein slideably coupling thecarriage with the guide rails includes attaching guide members to anunderside of a generally planar carriage plate and coupling the guidemembers with the guide rails, wherein the guide members are configuredto slideably engage a corresponding one of the guide rails.
 27. Themethod of claim 23, further comprising coupling at least one pair ofbrackets to an upper surface of a generally planar carriage plate androtatably mounting the lugs to corresponding ones of the brackets tothereby form the carriage.
 28. The method of claim 23, wherein couplingthe brackets to the carriage plate includes attaching the brackets tothe carriage plate with bolts that extend through the carriage plate.29. The method of claim 27, wherein each of the lugs is mounted on acorresponding shaft press fitted through the lug, and rotatably mountingthe lugs to the brackets includes placing the shafts throughcorresponding ones of the brackets.
 30. The method of claim 26, whereincoupling the hydraulic cylinder to the carriage includes coupling thehydraulic cylinder to an alignment coupler.